Why do some pilots consider speed control to be optional??

[NigelOnDraft]

I make all efforts to adhere to ATC speed requests. However, I do wish sometimes ATC understood:

1. Being asked to speed up to >300K in the same sentance as "expect 10-15mins delays" is just asking my employer to tear up £50 notes in quick succession.
2. Asking someone, from level flight, at say 270K as requested, to lose 10,000' in 25NM, with a tailwind is just not going to work.
3. Asking us, directly or indirectly, to break the TCAS V/S limits is going to be refused.
4. I will refuse to go >270K in turbulence if I judge it unsafe, or even unnecessarily uncomfortable.

I appreciate pilots will have different speeds they wish to fly - but I think ATC have some responsibility towards the planet and not burning fuel totally unnecessarily